Opportunity Analysis of Signal Management for Organization of Boot-Shaped Fuel Injection without Modifying Design of CRI Injector

Abstract

A calculated-experimental analysis of the opportunity of getting the boot-shaped front edge of the injection rate (boot injection) was performed. The research was carried out with Common Rail injectors (CRI) of the most widely used designs: CRI No 1 distinguished by its control valve with locking cone and valve piston; CRI No 2 with its fuel pressure balanced control valve, a channel in the piston and increased internal volume; CRI NO 3 distinguished by its control valve having a flat latch and needle valve which is not closing the fuel drain hole when it is in the highest position; CRI No 4 with partial closing of the control fuel drain hole. It was demonstrated that friction in the couple: control valve piston - guiding surface of the CRI No 1 hampers realization of the boot-shaped front edge of the injection rate due to its smoothening. The CRI No 2 enables to get the boot-shaped injection rate only in case of small pressures in the common rail (p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cr</sub> ≤ 50 MPa). This is explained by particular features of its control valve design. The CRIs No 3 and 4 ensure the boot-shaped injection rate at various pressures in the common rail. It was shown by the example of the CRI No 4 that instability in case of a boot-shape injection rate is comparable with instability of the primary fuel injection which is widely used for the organization of working processes of diesel engines having Common Rail type fuel systems.